Disks are presently employed to store information in digital form on the surface of a recording medium layer formed on the disk. The information can be recorded on (written to) or read from the recording surface by magnetic, magneto-optic or optic systems. In a typical system it is intended that the information stored on these disks be retrieved and loaded into a computer system quickly and easily without error. It has been found that magnetic particles as well as seemingly innocuous things such as fingerprints, dust particles or smoke particles can contaminate a disk and cause a read/write head to bounce over the contamination and disrupt the flow of information. This misreading of information is often referred to as "dropout" and is one of the most serious problems encountered in transferring information between a disk drive and a computer.
To overcome the dropout problem, disk cartridges are designed to provide a substantially closed and dust free environment for the disk. However, contaminants can infiltrate the disk through the hub or read/write window of the cartridges. Thus it is desirable to include a liner within the cartridge placed in contact with the disk to remove wear particles from the magnetic surface as well as other contaminants from the surface of the disk.
It is known to form a diskette liner from nonwoven fibers bonded together with an adhesive binder. Examples of such adhesive-bond liners can be found in U.S. Pat. Nos. 4,251,843 to Masuyama, and 4,354,213 and 4,419,164 to Martinelli which typically contain between twenty (20) and fifty (50) percent by weight of binder to achieve a bonding strength sufficient to maintain fabric integrity. The high amount of binder in adhesive-bond liners tends to coat the fibers with a plastic film, which results in a low cleaning ability. It also requires that binders of low glass transition temperature be used, in order to avoid excessive stiffness, but the tradeoff is reduced durability. It also requires conditioning chemicals, such as additional surfactants, anti-foams, and cross-linkers, to stabilize the binder solution, which presents a greater risk that such chemicals will be degraded (formaldehyde from cross-liners) or transported (surfactants and anti-foams made mobile by humidity) onto the disk media where they can cause damage or reduced durability.
Thermal-bond fabrics are also used for diskette liners, but they generally have a lower strength and stiffness and a higher level of debris. Also, significant amounts of free fiber pieces and other debris can come from the areas of the liner fabric that are cut during diskette manufacturing. U.S. Pat. Nos. 4,223,361 to Zaitsu, 4,414,597 to Cornin, 4,586,606 and 4,610,352 to Howey, 4,655,348 to Takagi, 4,680,661 to Oishi, and 4,803,584 to Doi show various improvements for reducing debris from and/or strengthening of thermal-bond liners by additional thermal bonding in or around the liner or through the use of stiffener layers or anti-dust layers or materials. The additional layers, dust prevention, and strengthening procedures tend to make the manufacturing process more costly and complicated.
U.S. Pat. No. 4,845,583 to Zimmerman discloses a powder-bonded nonwoven liner fabric which increases the strength and reduces the probability of debris from cut areas during diskette manufacturing. The powder is a thermoplastic adhesive material that is evenly deposited on a fiber web in an amount of approximately ten (10) to twenty (20) percent of the total fabric weight. Upon heating, the powder fuses and bonds the fibers of the web. The powder-bond fabric is deemed to have smaller and more widely distributed bond areas and a higher frequency of bond sites as compared with a thermal-bond fabric.
U.S. Pat. No. 4,791,516 to Seto discloses a treatment of a thermal-bond liner fabric with binder solution so that a higher concentration of the binder of about fifty (50) percent by weight of fabric is provided on the media-contacting side, and a lesser concentration of about five (5) percent is provided through the interior of the liner to the side adjacent the holder wall. Although it provides stiffness and reduced fibrous debris, the high level of binder at the media-contacting side tends to form a plastic coating that reduce cleaning ability. U.S. Pat. No. 4,998,176 also discloses a liner made of thermally bonded fibers which contains binder resin in an amount of up to 10% (5% used in the examples), in which more resin is present in the non-compression part than in the compression part of the fabric.